1. Field of the Invention
The invention relates generally to communication systems and, more particularly, to methods and systems for measuring available bandwidth on internet access networks.
2. Related Art
A conventional technique for estimating the available upstream link bandwidth for a communications device operating on an internet access network includes a manually-configured or self-installed installer unit at the user location. The installer sets a variable in the communications device corresponding to the available upstream bandwidth. A disadvantage of this bandwidth estimation technique is that the variable is not updated periodically to reflect changing conditions on the network. For example, if the actual available upstream bandwidth changes over time, then the value set by the installer will be inaccurate and could even “punish” the user if the value set by the installer is less than the amount of upstream bandwidth that is actually available on the network at a given time.
In another conventional bandwidth estimation technique, the communications device establishes a transmission control protocol (TCP) connection with a server that uses TCP to measure upstream bandwidth availability. During the estimation process, TCP ramps up the bit rate of the data through the connection until it converges upon the size of the upstream link. A problem with TCP bandwidth estimation is the communications device might not have a server readily available with which to establish the TCP connection. Also, TCP bandwidth estimation can be intrusive. During the estimation process, TCP ramps up the bit rate fairly aggressively such that it might interfere with existing data services on the network. For example, for voice over IP (VoIP), TCP bandwidth estimation can introduce jitter and latency to a call. Accordingly, TCP bandwidth estimation should be limited to off-hours periods. This limitation is undesirable, however, because it precludes the server from obtaining frequent updates to assess changing conditions on the network.
In yet another conventional bandwidth estimation technique, a communications device, such as a cable modem, is connected to a standalone multimedia terminal adapter (MTA). The MTA sends packets to the communications device and queries what bandwidth is available. This bandwidth estimation technique is problematic because it relies on proprietary hardware and software to perform the query.
What is needed, therefore, is an automatic, non-intrusive, device-independent, and connection-independent technique for estimating the available upstream bandwidth for a device operating on an internet access network.